# alloc_fence.ludic - the allocation fence (docs/plan 25.1) judges frames once play has settled.
# Everything a frame makes here is gone by the frame's end or goes on being reused: text only
# compared (freed once compared), records held from before play written in place. No frame
# keeps anything, so the run - which fails by default when one does - prints
# `frames 300 kept 0 bad 0`.
program AllocFence {
  property Box { a: int = 0 }

  function round(i: int, kept: []Box) -> int {
    var bad = 0
    if `{i}-{i * 2}` != string(i) + "-" + string(i * 2) { bad += 1 }
    if `lake {i}` == "" { bad += 1 }
    for k in 0 .. len(kept) { kept[k].a = i + k }   # records reused: List.clear and new ones would keep the old
    return bad
  }

  entry {
    var kept = new []Box
    for k in 0 .. 8 { push(kept, new Box) }
    Mem.play()
    Mem.settled()
    var bad = 0
    var frames = 0
    for i in 0 .. 300 {
      bad += round(i, kept)
      Mem.frame()
      frames += 1
    }
    let kept_now = Mem.kept()                     # read before the line below makes its text
    print(`frames {frames} kept {kept_now} bad {Mem.bad_frames()}`)
  }
}